Filtered Cathodic Arc Research Articles

Development of Ti/Ti-DLC multilayers on magnesium alloys. Part 1: Microstructure and mechanical properties

To improve both the corrosion resistance and wear resistance of magnesium alloys, titanium-diamond-like carbon (Ti-DLC) monolayer and Ti/Ti-DLC multilayer films with two periods were applied to AZ31 magnesium alloys through filter cathodic vacuum arc deposition technology. The Ti-DLC monolayer film exhibited an amorphous structure doped with TiC nanocrystals. After introducing the Ti sublayer, the Ti/Ti-DLC multilayer films exhibited a layered structure, resulting in improved adhesion strength and fracture toughness and lower hardness. Compared with the (Ti/Ti-DLC)4 multilayer film with a smaller period, the (Ti/Ti-DLC)2 multilayer film with a lager period exhibited better adhesion strength, higher fracture toughness, hardness, ID/IG ratio, and lower residual stress owing to its thicker Ti sublayers.

Development of Ti/Ti-DLC multilayers on magnesium alloys — Part 2: Corrosion and wear resistance

To improve corrosion and wear resistance of magnesium alloy, the Ti-DLC monolayer and Ti/Ti-DLC multilayer films were deposited on AZ31 magnesium alloys by filter cathodic vacuum arc deposition technology. All coatings showed good corrosion and wear resistance, and low friction coefficient. The corrosion resistance of the coated samples, from high to low, was Ti/Ti-DLC)2 multi coated-, Ti-DLC mono coated-, and Ti/Ti-DLC)4 multi coated samples. That is because the good toughness and film/substrate deformation coordination of multilayer films were beneficial for improving the corrosion resistance of coating, but the thinner Ti sublayer increased the risk of corrosion liquid penetrating the coating. Under friction test under 5 N load for 30 min, the Ti-DLC monolayer film showed best wear resistance with lowest wear rate as its combination effects of high hardness and good toughness. Whereas, under higher load, the higher toughness and film/substrate deformation coordination of multilayer films played a more positive role in its wear life. Under load of 10 N, comparing to the Ti-DLC monolayer film, the (Ti/Ti-DLC)4 multi and (Ti/Ti-DLC)2 multi films improved wear life by 15 % and 36 %, respectively. The (Ti/Ti-DLC)2 multi film had the best corrosion resistance and wear life.

Enhancement of discharge and mechanical properties of ta-C films by pulse-enhanced cathodic arc deposition

A home-made straight-duct filter cathodic vacuum arc system was used to synthesize tetrahedral amorphous carbon (ta-C) films. The ta-C films were fabricated using both direct-current cathodic arc evaporation (DC-CAE) and pulse-enhanced cathodic arc evaporation. A series of films were prepared as a function of pulse current ranging from 500 to 1000 A compared with 80 A direct current. The introduction of pulse current could markedly increase instantaneous input power (Wiip). The pulse-enhanced Wiip led to the increase in average substrate current from 0.46 to 1.07 A. Moreover, compared with DC-CAE, the pulse current of 1000 A significantly increased the intensity ratios of C II/(C I + C II) and C II/Ar II by about 65% and 130%, respectively. All the results showed that the pulse-enhanced Wiip substantially improved the evaporation and ionization rate of graphite. However, due to thermal-induced graphitization conversion, the threshold pulse current was 800 A. Under this pulse current, the film exhibited the smallest ID/IG (0.26) as well as the highest sp3 fraction (64.3%). Correspondingly, the highest hardness (≈40 GPa) and the preferable toughness (H/E* of 0.12 and H3/E*2 of 0.52) were simultaneously achieved.

Development of irradiation-resistant enriched 12C targets for astrophysical [formula omitted] reaction measurements

The production of irradiation-resistant enriched 12C target is one of the key technologies in the direct measurement of the 12C(α,γ)16O reaction at energies of astrophysical interest. In this work, we produced the enriched Ti12C targets on Ta substrates via the filter cathodic vacuum arc (FCVA) technology. The target stability under the bombardment of a high-intensity 4He beam was investigated by monitoring the γ-ray yields of the 12C(p,γ)13N reaction regularly. A 25% deterioration of 12C in the target was observed after bombardment by a 740 keV, 500 μA 4He2+ beam with a charge of 280 C, which is stronger than the implanted targets developed before. Furthermore, the 13C/12C ratio in the Ti12C target was measured to be (1.1±0.3)×10−4, which can meet the requirement of the 12C(α,γ)16O measurement at the China JinPing underground Laboratory (CJPL).

Influence of carbon content on the structure and tribocorrosion properties of TiAlCN/TiAlN/TiAl multilayer composite coatings

To improve the tribocorrosion performance of protective coatings in a real running environment under the synergistic action of friction and corrosion, the development of advanced coatings with excellent properties and research on the tribocorrosion mechanism are important. Based on the design principle of functional gradients/multilayers, TiAlCN/TiAlN/TiAl multilayer composite coatings were prepared by the filter cathodic vacuum arc (FCVA) technique. The effects of carbon contents on the structure, friction, corrosion and tribocorrosion properties were studied. With increasing carbon content, the composite structure of crystalline TiAlCN/amorphous carbon significantly improves the corrosion and wear resistance of the coatings. The TiAlCN/TiAlN/TiAl coating with the highest carbon content of 22.1 at.% has the best resistance to corrosion and wear but shows the worst tribocorrosion resistance under the synergistic action of friction and corrosion. The TiAlCN/TiAlN/TiAl coating with a carbon content of 12.4 at.% exhibits the best tribocorrosion resistance with the minimum values of the cathodic shift of open circuit potential (ΔOCP), coefficient of friction(COF) and wear rate. The results indicate that an overall optimized TiAlCN/TiAlN/TiAl multilayer composite coating with appropriate amounts of amorphous carbon phase and the strongest crystallized form of TiAlCN has excellent performance in terms of ultrahigh hardness (44.36 GPa), high H/E, the dense structure and stable passivation layer to achieve good tribocorrosion resistance.

A Comparative Performance Analysis of Uncoated and Coated WC Drills during Forging Brass Drilling Operation

In this study, the performances of the WC tools coated with TiCN and AlCrN by filter cathodic arc in hole drilling of forging brass were investigated and compared with that of uncoated one. The performances were evaluated using the exit burr height (EBH) criterion and process capability indices as a function of number of parts drilled with the three types of drills. The results showed that there were significant differences of EBH and the process capability index of Cpm during drilling of the workpieces with the three types of drills. The desired EBH values of 0.152-0.1535 mm, roughness values of 2-3 µm and drilled diameters of 17.79-17.8 mm were achieved with the appropriate operating conditions including cutting speeds and feed rates ranging from 0.17 to 0.19 mm/rev and 55 to 57 m/min, respectively.

Tetrahedral amorphous carbon prepared filter cathodic vacuum arc for hole transport layers in perovskite solar cells and quantum dots LEDs

ABSTRACT (ta-C) films coated through the filtered cathodic vacuum arc (FCVA) process as a hole transport layer (HTL) for perovskite solar cells (PSCs) and quantum dot light-emitting diodes (QDLEDs). The p-type ta-C film has several remarkable features, including ease of fabrication without the need for thermal annealing, reasonable electrical conductivity, optical transmittance, and a high work function. X-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy examinations show that the electrical properties (sp3/sp2 hybridized bond) and work function of the ta-C HTL are appropriate for PSCs and QDLEDs. In addition, in order to correlate the performance of the devices, the optical, surface morphological, and structural properties of the FCVA-grown ta-C films with different thicknesses (5 ~ 20 nm) deposited on the ITO anode are investigated in detail. The optimized ta-C film with a thickness of 5 nm deposited on the ITO anode had a sheet resistance of 10.33 Ω−2, a resistivity of 1.34 × 10−4 Ω cm, and an optical transmittance of 88.97%. Compared to the reference PSC with p-NiO HTL, the PSC with 5 nm thick ta-C HTL yielded a higher power conversion efficiency (PCE, 10.53%) due to its improved fill factor. Further, the performance of QDLEDs with 5 nm thick ta-C hole injection layers (HIL) showed better than the performance of QDLEDs with different ta-C thicknesses. It is concluded that ta-C films have the potential to serve as HTL and HIL in next-generation PSCs and QDLEDs.

Effect of substrate bias on the tribological behavior of ta-C coating prepared by filtered cathodic vacuum arc

Tetrahedral amorphous carbon (ta-C) films were coated on the tungsten carbide cobalt by using filter cathodic vacuum arc (FCVA). All the specimens were coated at different bias voltage, such as 0 V, 40 V, 80 V, 120 V, and 160 V. The tribological behavior of all these specimens were evaluated by using a ball-on-disc type of tribo-test. Raman analysis was used in this research for investigating the bond structure in the coating films. From the experiment result shown the variation of the bias voltage of the ta-C coating do not bought to the change of the mechanical properties. As well as for the tribological aspect. Whereas, it only bought to the influence of the wear properties. The lowest wear rate result were found from the ta-C film that coated under 40V. This was due to the surface contact area and the surface roughness properties different at the different bias voltage.

Structure and properties of TiN coatings produced with PIII&D technique using high efficiency rectilinear filter cathodic arc plasma

In this study, the effects of pulse bias application during plasma immersion ion implantation and deposition (PIII&D) on the structural, mechanical and tribological properties of TiN coatings are investigated. The coatings produced with the application of pulsed bias showed several distinct changes, depending on the type and magnitude of the bias potential. With increasing pulse bias potential, preferred orientation of crystallite planes parallel to the coating surface, gradually changed from (111) to (220), accompanied by a structural transition from Zone T to Zone 2 type structure. Internal stress levels also showed a dependence on the type of bias and bias potential. The results of wear tests clearly revealed significant improvement of tribological properties with the application of pulsed bias.

Chemical Bonding in Composite SiNx/Diamond-Like Carbon Films Prepared by Filter Cathodic Arc Deposition of Graphite Incorporated with Radio Frequency Sputtering of Silicon Nitride

SiNx and diamond-like carbon (DLC) films were prepared simultaneously on Si substrates by the RF magnetron sputtering of a silicon nitride (Si3N4) target and the filtered cathodic arc (FCA) deposition of graphite, respectively. The RF power was fixed at 100 W, while the arc current of graphite for the FCA deposition was varied from 20 to 80 A. The structure of composite SiNx/DLC films was investigated by Raman spectroscopy. The chemical composition and chemical state of the films were analyzed by X-ray photoelectron spectroscopy (XPS). Results revealed that the atomic concentration of carbon (C) increased, while those of silicon (Si) and nitrogen (N) decreased with increasing arc current. In addition, the sp3 content in the composite films was found to increase with the arc current. This result indicates that the structure and property of the composite films can be controlled according to their required applications by varying the arc current.

Carbon Overcoat Oxidation in Heat-Assisted Magnetic Recording

Due to the ever increasing demand for higher storage capacity in disk drives, novel techniques to read and write information, such as heat-assisted magnetic recording are being developed. However, the recording temperatures impact not only the media but also the carbon overcoat that is used to protect both the media and writing head. In this paper, we discuss the effect of thermal annealing on the rate of carbon erosion on overcoats deposited using two different techniques, viz. filtered-cathodic arc and plasma-enhanced chemical vapor deposition.

Thermal Heating Effect on Structural and Mechanical Property of Diamond-Like Carbon Film Prepared by Filtered Cathodic Arc

Diamond-like carbon (DLC) films were deposited on magnetic recording head by Filtered Cathodic Arc (FCA) technique and a-Si base material was ion beam deposited as seed layer. To investigate the thermal stability of stack film, repeated cycle thermal heating at 200 °C was employed. Raman spectroscopy and nanoindenter (Hysitron) were performed to understand film structure and mechanical property as a function of thermal heating conditions. The roles of heating in material composition and wear behavior of DLC films are discussed. The Raman spectra revealed that G position, FWHM of G peak and Id/Ig change as with increasing heating cycle which agreed well with wear depth measured. With these results suggesting DLC film degraded with repeated heating at 200 °C.

Mechanical Properties of Composite SiNx/DLC Films Prepared by Filtered Cathodic Arc of Graphite Incorporated with RF Sputtering of Silicon Nitride

Composite SiNx/DLC films were deposited on Si substrate by RF magnetron sputtering of silicon nitride (Si3N4) target simultaneously with filtered cathode arc (FCA) of graphite. The RF power was fixed at 100 W whereas the arc currents of FCA were 20, 40, 60 and 80 A. The effects of arc current on the structure, surface roughness, density and mechanical properties of SiNx/DLC films were investigated. The results show that the arc current in the studied range has effect on the structure, surface roughness, density and mechanical properties of composite SiNx/DLC films. The composite SiNx/DLC films show the sp3 content between 53.5% and 66.7%, density between 2.54 and2.98 g/cm3, stress between 1.7 and 2.2 GPa, and hardness between 35 and 51 GPa. Furthermore, it was found that the density, stress and hardness correlate linearly with the sp3 content for composite SiNx/DLC films.

Wear Behavior of Diamond-Like Carbon Film Coated by Filtered Cathodic Arc

Diamond-like carbon (DLC films were deposited on NiFe coupon by Filtered Cathodic Arc (FCA) technique. Two different DLC thicknesses were selected to compare thickness dependency on film properties change. The mechanical property as wear resistance under cyclic heating condition was investigated by nanoindenter (Hysitron). The detail of DLC film composition change was also studied using X-ray Photoelectron Spectroscopy (XPS). The roles of heating in material composition and wear behavior of DLC films are discussed. The effect of DLC film thickness is also considered. The results showed that thinner DLC (2 nm) has higher carbon oxidation resulting that deteriorate in wear resistance as compare to thicker one (5 nm). The heating accelerates these oxidation and wear in this study. .

Raman Characterization and Mechanical Properties of the Silicon Nitride/Diamond-Like Carbon Composites Film Prepared by Co-Deposition of RF Magnetron and Filter Cathodic Arc

The silicon nitride/diamond-like carbon composites were fabricated using co-deposition sources. The RF magnetron was used to deposit silicon nitride simultaneously with cathodic arc deposition of carbon. The condition of RF magnetron sputtering for silicon nitride was fixed at 0.6mTorr, RF power 200 watts and 100 watts to maintain deposition rate of silicon nitride. The arc current was conditionally manipulated in this study to vary carbon deposition rate, resulting a change in composite ratio between two materials. Raman characterization and mechanical properties such as film stress and hardness were discussed as a function of deposition rate ratio. It was found that the variation of film stress follows carbon deposition rate. The Raman spectra show that the G-peak position shift to the lower wavenumber while decreasing arc current and deposition rate of carbon.

Thermal Stability Evaluation of Diamond-like Carbon for Magnetic Recording Head Application using Raman Spectroscopy

Diamond-like carbon (DLC) films were deposited on magnetic recording heads using filter cathodic arc for improvement of tribological property and corrosion protection. To increase the areal density of magnetic storage, the thickness of DLC film has to be decreased to less than few nanometers. In addition, the heat occurred at the head-disk interface during the operation can impact on the properties and protective performance of DLC films. In this work, the effect of heat on the properties of DLC films was investigated by visible Raman spectroscopy. The Raman spectra of DLC film as a function of heating temperature and time were carried out. The Raman spectra revealed that the degree of graphitization of the DLC films increased with increasing of temperature and time. The relative Raman intensity was found to decrease with possibility of sp3/sp2 ratio decreasing in the films. It can be concluded that the thermal stability of DLC film degraded at high temperature environment.

Effects of Negative Bias Voltage on Structure and Mechanical Properties of DLC Films Synthesized by FCVA Deposition

Diamond-like carbon (DLC) films have been given great attention in the last twenty years and applied in many fields due to its super mechanical property. In this paper, DLC films were prepared by filter cathodic vacuum arc (FCVA) deposition under different negative bias voltage. No spalling was found in all of as-prepared DLC films. X-ray photoelectron spectroscopy (XPS), Raman spectra were employed to analyze composition and structure, the results showed that as-prepared DLC films had tendency of graphite with increase of negative bias voltage. Mechanical properties were characterized by micro-hardness and pin-on disc tests, the results showed that the hardness of DLC films decreased with bias voltage, but still kept good wear resistant.

High Rate Deposition of High Quality ZnO:Al by Filtered Cathodic Arc

ABSTRACTHigh quality ZnO:Al (AZO) thin films were prepared on glass substrates by direct current filtered cathodic arc deposition. Substrate temperature was varied from room temperature to 425°C, and samples were grown with and without the assistance of low power oxygen plasma (75W). For each growth condition, at least 3 samples were grown to give a statistical look at the effect of the growth environment on the film properties and to explore the reproducibility of the technique. Growth rate was in the 100-400 nm/min range but was apparently random and could not be easily traced to the growth conditions explored. For optimized growth conditions, 300-600 nm AZO films had resistivities of 3-6 x 10-4 Ωcm, carrier concentrations in the range of 2-4 x 1020 cm3, Hall mobility as high as 55 cm2/Vs, and optical transmittance greater than 90%. These films are also highly oriented with the c-axis perpendicular to the substrate and a surface roughness of 2-4 nm.

Tribological performance of DLC coatings on UHMWPE

Diamond like carbon (DLC) coatings were deposited by several methods (ion beam assisted evaporation, magnetron sputtering, filter cathodic arc, and plasma enhanced chemical vapor deposition) onto medical grade ultra-high-molecular weight polyethylene (UHMWPE) discs. The chemical characteristics and mechanical properties of the deposited DLC coatings were studied by Raman spectroscopy and nanoindentation, respectively. In addition, a set of tribological tests was conducted at human body temperature and under bovine serum lubrication against alumina balls. After testing, wear tracks were both visually inspected and documented using confocal microscopy. Visual inspection of the wear tracks confirmed that the DLC coatings were completely removed in all cases, the only exception being the DLC coating prepared by magnetron sputtering with thickness about 0.5 microns. Although this type of DLC coating exhibited the highest friction coefficient, and therefore it suggested a somewhat lower resistance to abrasive/adhesive wear conditions, no evidence of cracking or delamination was observed after the high contact pressure wear testing. This fact points out a good substrate-coating adhesion, and confirms magnetron sputtered DLC as a potential coating for orthopaedic applications.

Design and rapid prototyping of DLC coated fractal surfaces for tissue engineering applications

Several medical devices (both implantable and for in vitro diagnosis) benefit greatly from having microtextured surfaces that help to improve and promote phenomena such as osteointegracion and cell / tissue growth on the surface of a device. Normally, the use of abrasives or chemical attacks are employed for obtaining such surface microtextures, however, it is sometimes difficult to precisely control the final surface characteristics (porosity, roughness, among others) and consequently the related biological aspects. In this work, we propose an alternative process based on the use of fractal surface models for designing special surfaces, which helps controlling the desired contact properties (from the design stage) in multiple applications within biomedical engineering, especially regarding tissue engineering tasks. Manufacturing can be directly accomplished by means of rapid prototyping technologies. This method supposes a focus change from a conventional "top-down" to a more versatile "bottom-up" approach.Finally, in order to improve the possible biological response, the surfaces of the designed devices were coated with hydrogen-free amorphous carbon (a-C) thin films, known to be highly biocompatible materials. The films were deposited at room temperature using the vacuum filter cathodic arc technique. Our first prototypes have helped verify the viability of the approach and to validate the design, manufacturing and coating processes.